1. Field of the Invention
This invention relates to a one chip, direct drive and keyboard sensing scheme for a light emitting diode or digitron display, such as those used in an electronic calculator, or the like.
2. Prior Art
A conventional scheme for driving either a light emitting diode or digitron display, such as those found in an electronic calculator, typically requires at least two semiconductor chips. A first chip includes respective circuitry for driving the light emitting diode display. A second chip includes respective circuitry for driving the digitron display. Frequently, buffering components are required to interface each chip with its respective display. As a result, the size and corresponding cost of a conventional driver circuit is undesirably increased. Moreover, relatively complex signal processing means are frequently required to evaluate the output signals of each of the first and second chips in order to determine the switch position of a keyboard key.